dont fly off the handle

Dont fly off the handle is an expression of warning to someone else to regain their self control and not become a danger to others. This cliche is typically told to someone who is getting very angry and agitated where they seem to be losing their self control and may act out of anger in a way that can possible injure somebody else. Dont fly off the handle is a way to warn them of what may be coming if they arent careful to control themselves.